Hawaii tops the list. Missouri has the cheapest gas.New York (CNN/Money) -- The average price for regular gasoline on Monday, March 7, was $1.98 a gallon, down from $1.90 per gallon a month earlier, according to AAA.

A year earlier, the average price of a gallon of regular gasoline was $1.73.

Hawaii leads the nation at $2.42 a gallon for regular, followed by California at $2.25 and Nevada at $2.20.

These figures are averages for each state. Gas prices within each state can vary greatly.

The AAA's Daily Fuel Gauge Report is based on a survey of over 60,000 self-serve stations.